Re: [ANNOUNCE] 5.10.162-rt78

[Salvatore Bonaccorso <carnil@debian.org>]

Hi Luis, all,

On Thu, Jan 19, 2023 at 10:16:34AM -0300, Luis Claudio R. Goncalves wrote:
> On Thu, Jan 19, 2023 at 12:38:25PM +0100, Pavel Machek wrote:
> > Hi!
> > 
> > > > I'm pleased to announce the 5.10.162-rt78 stable release.
> > > > 
> > > > You can get this release via the git tree at:
> > > > 
> > > >   git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git
> > > > 
> > > >   branch: v5.10-rt
> > > >   Head SHA1: 143ef105f40a65f3ddd57121d4b4bc36eb10cc06
> > > > 
> > > > Or to build 5.10.162-rt78 directly, the following patches should be applied:
> > 
> > > I see that vanilla 5.10.162-rt78 fails to build with arm64 defconfig. [0] Full log [1]
> > > Any pointers on what maybe wrong?
> > 
> > We see the same failure. 
> > 
> > >   AS      arch/arm64/kernel/entry.o
> > > arch/arm64/kernel/entry.S: Assembler messages:
> > > arch/arm64/kernel/entry.S:763: Error: immediate out of range at operand 3 -- `and x2,x19,#((1<<1)|(1<<0)|(1<<2)|(1<<3)|(1<<4)|(1<<5)|(1<<6)|(1<<13)|(1<<7))'
> > > make[2]: *** [scripts/Makefile.build:367: arch/arm64/kernel/entry.o] Error 1
> > > make[1]: *** [scripts/Makefile.build:503: arch/arm64/kernel] Error 2
> > > make: *** [Makefile:1837: arch/arm64] Error 2
> > 
> > The line is:
> > 
> > >        and     x2, x19, #_TIF_WORK_MASK
> 
> I believe this is related to the arch/arm64/include/asm/thread_info.h
> changes in 5.10.162-rt78, specifically:
> 
>     79a9991e87fe arm64: add support for TIF_NOTIFY_SIGNAL
>     1ba44dcf789d Merge tag 'v5.10.162' into v5.10-rt
> 
> The first one is the original change, coming from stable v5.10.162 and the
> second one has the merge conflict I fixed in that file due to the existence
> of TIF_NEED_RESCHED_LAZY in PREEMPT_RT.
> 
> It escaped me that having TIF_NEED_RESCHED_LAZY set to 13 breaks the AND
> statement reported above. Looking at
> 
>     b5a5a01d8e9a arm64: uaccess: remove addr_limit_user_check()
> 
> specially this note
> 
>     To ensure that _TIF_WORK_MASK can be used as an immediate value in an
>     AND instruction (as it is in `ret_to_user`), TIF_MTE_ASYNC_FAULT is
>     renumbered to keep the constituent bits of _TIF_WORK_MASK contiguous.
> 
> I understand that I need to either have to renumber TIF_NEED_RESCHED_LAZY
> to 8, with the risk of breaking something else, or backport commit
> b5a5a01d8e9a in order to remove TIF_FSCHECK and then safely renumber
> TIF_NEED_RESCHED_LAZY.
> 
> Guidance is welcome here :)

Should we loop in here Jens, as having some overview of the needed
changes for io_uring rebase in the 5.10.y version? (doing so in the
mail).

Regards,
Salvatore